Blog

When to Plant Tomatoes in Anchorage Municipality, AK

Anchorage Municipality, Alaska Zone 5a May

Anchorage Municipality, Alaska gardeners: here's your May plan

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Anchorage Municipality, Alaska.

Avg. last frost May 15
Avg. first frost September 19
Soil temp (4") 46°F
Watering Critical
Pest pressure Low
Daylight 17.1 hrs
  1. Plant out tomatoes

    Frost risk is low now in Anchorage Municipality, Alaska. If you've been covering beds overnight, you can stop.

  2. Outdoor sowing time: tomatoes

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

Instant PDF download. No spam, unsubscribe any time.

Tomatoes are the most popular home garden crop, available in thousands of varieties from tiny cherries to massive beefsteaks. They are warm-season plants needing full sun.

Anchorage Municipality, Alaska is in USDA Zone 5a. The average last spring frost is May 15 and the first fall frost is September 19, giving you a growing season of approximately 127 days.

At an elevation of 2,537 feet, Anchorage Municipality receives approximately 20.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 71°F, so choose short-season varieties of Tomatoes to ensure they mature before fall.

Anchorage Municipality, AK (Zone 5a) Short season
127 days
Last Spring Frost May 15
127 growing days
First Fall Frost September 19

Anchorage Municipality Soil Profile

Soil Type

Silt Loam

Soil pH

4.9-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 9 Transplant: May 18 🍅 Harvest: Jul 20 – Sep 28
Recommended (50%) ✗ May not fit
Start indoors: Mar 20 Transplant: May 29 🍅 Harvest: Jul 31 – Oct 9
Safe Start (90%) ✗ May not fit
Start indoors: Apr 7 Transplant: Jun 16 🍅 Harvest: Aug 18 – Oct 27

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Soil Compatibility in Anchorage Municipality

How your county's soil matches Tomatoes's growing requirements.

Soil pH

Your soil pH (4.9–6.5) is more acidic than Tomatoes prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Anchorage Municipality is excellent for Tomatoes — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Tomatoes.

Organic Matter

Organic matter is excellent (5.2%) — Tomatoes will thrive.

How to Plant Tomatoes

0.5"
Planting Depth
24"
Between Plants
36"
Between Rows

Succession Planting Tomatoes

2
successive plantings in your 127-day season

Sow every 6.9 weeks. Last sowing by Jun 26 to harvest before frost.

Plant Water Budget

Plant needs
1.2″/week
Rainfall provides
0.7″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 187 gal / 100 sq ft

Monthly Watering Guide for Tomatoes

Tomatoes needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.

Month Tomatoes Needs Rainfall You Supplement Action
Jan 1" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 0.8" 0" ❄️ Dormant
Apr 0.6" 0" ❄️ Dormant
May 5.2" 0.9" 4.3" 🚿 Regular watering
Jun 5.2" 1.5" 3.7" 🚿 Regular watering
Jul 5.2" 2.6" 2.6" 🚿 Regular watering
Aug 5.2" 3.3" 1.9" 💧 Light watering
Sep 5.2" 3.2" 2" 💧 Light watering
Oct 2.4" 0" ❄️ Dormant
Nov 1.7" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Anchorage Municipality). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Tomatoes Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Tomatoes needs ~236 GDD — county provides 412 GDD Excellent fit

Tomatoes Planting Timeline — Anchorage Municipality, AK

Tomatoes Planting Calendar

Activity When Date Range
Start Indoors March 20 Mar 20 – Apr 3
Transplant Outdoors May 29 May 29 – Jun 12
Direct Sow May 22 May 22 – Jun 12
Harvest July 31 Jul 31 – Oct 9

Plant 0.5" deep · 24" apart · Rows 36" apart

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors
May Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July Harvest
August Harvest
September Harvest
October Harvest
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.2"/week · Only during dry spells

📅 Days to Maturity

60–85 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 5a

📆 Growing Season

127 days in Anchorage Municipality

Growing Tips for Tomatoes in Anchorage Municipality

Direct sow Tomatoes outdoors after May 15 in Anchorage Municipality when soil has warmed and frost danger has passed.

Common pests for Tomatoes in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.

Anchorage Municipality receives only 20" of rain annually. Tomatoes needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Start seeds indoors 6-8 weeks before last frost. Bury transplants deep to encourage rooting along the stem. Provide consistent moisture to prevent blossom end rot and cracking.

Recommended Tomatoes Varieties for Anchorage Municipality

Choose determinate, early-maturing varieties for your short season

Early Girl (52d) Stupice (55d) Glacier (55d) Sub Arctic Plenty (45d)

Companion Planting

Good Companions

Avoid Planting Near

  • Cabbage
  • Fennel
  • Potatoes

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Tomatoes Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Scoop seeds from ripe fruit; ferment 2-3 days to remove gel coating.
Storage Store airtight; viable 4-6 years at 35°F, under 45% humidity.

Isolate 25 ft between varieties for purity. Use open-pollinated varieties for true-to-type seeds.

Frequently Asked Questions

When should I plant Tomatoes in Anchorage Municipality, AK?

Anchorage Municipality is in Zone 5a with an average last frost of May 15. Plan your Tomatoes planting based on this frost date — see the calendar above for exact timing.

What planting zone is Anchorage Municipality, AK?

Anchorage Municipality, Alaska is in USDA Hardiness Zone 5a. The average last spring frost is May 15 and first fall frost is September 19.

🌱

Your Anchorage Municipality Garden Planner — Free

A 24-page printable planner built for Anchorage Municipality (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Anchorage Municipality, AK. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.